US1857370A - Removal of wax from oil - Google Patents

Description

v No Drawing.

Patented May 10, 1932 UNITED STATES STAN-ARI) R. FUN STEN, F HAVERFORD, AND IVAN M. PERKINS, OF PENFIELD, PENN SYLVANIA, ASSIGNORS TO THE ATLANTIC REFINING COMPANY, OF PHILADEL- PHIA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA nnnrovnr. on wax mom OIL Our invention relates to the art of removing wax from wax-containing oil, as petroleum, and more particularly to a process in which a substance is added to the wax-containing oil, thereby to condition the oil so that the wax may be more readily removed therefrom.

We have found that by adding a compound contained in coal tar or a component thereof to a wax-containing oil before the oil is subjected to any of the well-known separating operations, then after such addition subjecting the oil to a suitable separat ing operation, as for example, cold settllng, centrifuging, filtering, or the equivalent, the

7 wax will more readily separate from the oil than if such compound had not been added.

Furthermore, we have found that the coal tar compound may be added to the waxcontaining oil in any suitable manner, as for example, by first extracting coal tar with a suitable solvent such as benzol, alcohol, naphtha, or the like, and adding the extract to the wax-containing oil, or by filtering the wax-containing oil through coal tar or clay upon which the coal tar compound has been deposited, or by the direct addition to the oil of the coal tar compound or that portion of coal tar, as for example, coal tar pitch, which contains the compound. In either instance the coal tar compound is advantageously added to wax-containing oil while the oil is hot, preferably while the oil is at a temperature above 70 F., and in any event above the temperature to which the oil is to be chilled. We have found that it is preferable, to have coal tar present in the wax-containing oil in amounts less than 2% by weight of the oil.

The chemical formula of component fractions of coal tar which function most advantageously in agglomeratin the wax is not known with precision. It is sufficient to say that the coal tar compounds or fractions thereof which are employed in accordance with our process are among the higher mogeneral, that chilling of the wax-containing lecular weight, higher-boiling coal tar compounds' While the presence of the more volatile, lower-boiling compounds of coal tar is not set forth'as of particular advantage in the separation of'wax, yet the presence of one 1929. Serial No. 373,471.

or more such compounds in the coal tar compounds employed is not necessarily undesirable. Herein, and in the appended claims it is to be understood that the coal tar extracts or compounds referred to which cause agglomeration ofwax particles which in turn causes more ready separation of wax from oil, refer in particular to the components of the coal tar of boiling points or molecular weights, higher than those of the so-called tar pitch are at least in part or to substantial extent such compounds or extracts of higher boiling point and/or high molecular weight as will produce the desired agglomeration and/or separation of wax from oil.

After the addition of the coal tar compound to the oil it may be treated by any of the well-knownprocesses for removing wax from oil, as for example, by the cold settling process which involves chilling the oil and allowing it to stand, or by the centrifuging process which involves chilling the oil then passing it into a centrifuge, or by filtering the oil-wax mixture after chilling through a suitable filtering medium.

In separating wax from oil by processes involving chilling the temperature to which the wax-containing oil is chilled depends largely upon the particular pour desired of the ultimate oil product. We have found, in

oil to F. or below according to the pour desired, will produce satisfactory results by our process. However, we are not limited to any specific temperatures of chilling.

A particular advantage of our process is that the Wax content of the wax-containing oil forms larger crystals or crystal aggregates during chilling so that separation of solid 5 from liquid may be more readily efi'ected, as for example, by such'well-known separating processes as hereinbefore stated.

. As an example of our process but without intending to limit our invention thereto, a m lubricating oil containing Wax, more particularly a high viscosity fraction obtained from the non-cracking distillation of a mid-continent crude petroleum was diluted with naphtha using 70 parts of naphtha to 30 parts of oil. The dilutedoil was raised in temperature to about 130 F. and while at this temperature the oil was filtered through a bed of equal parts of coal tar pitch and clay such as fullers earth, of about ten inches in depth.

It is estimated that the oil after filtering contained about .3% of the desired coal tar compound. The oil was then cooled to +10 F. and maintained at that temperature in a settling pan for a period of twenty hours. Af-

ter such period it was found that the wax had settled to the bottom of the oil forming a distinct lower layer, while the upper layer was a clear substantially wax-free liquid and comprised about 54% of the total oil. A blank run under the same conditions except that no coal tar compound was added thereto showed no appreciable settling during the same period of time.

As specific examples of'the sources of the coal tar compound used in our process, such may be obtained from coal tar residues, or pitches, preferably of high melting point, as of the order of 400 F., or from high boiling point coal tar distillates, as for instance of a boiling point of the order of from 620 40 to 650 F. when distilled under a vacuum of 10 m, m. of mercury. Either the residue or the distillate may be incorporated with the wax-containing oil thereby to dissolve in the latter the desired coal tar material in suitable amounts, as for example by methods hereinbefore stated. I

Thus it will be seen that 'byadding a compmnfl derived from coal tar to a wax-containing oil there results the particularly desirable efiectofconditioning the oil so that the wax may be more readily separated therefrom both with regard to rate and completeness of separation.

It will be understood that in some instances itmay be. found unnecessary to dilute the wax-containing oil before chilling and therefore we do not contemplate limiting our invention in this respect. Furthermore, it is to be understood that our process may be used for the separation of-wax from wax-containing oil or mixture of wax-containing oils, more particularly for the removal of wax from petroleum oil, either crude petroleum or any wax bearing portion thereof, or mixture of them.

What we claim is:

1. A process for dewaxing a wax-containing oil involving separation of wax from oil, which comprises adding to the oil a highboiling compound contained in coal tar, thereby to condition the wax-containing oil to cause wax agglomeration, thereafter removing wax from the oil.

2. A process for dewaxing a wax-containing oil involving separation of wax from oil, which comprises adding to the oil a highboiling compound contained in coal tar, thereby to condition the wax-containing oil to cause wax agglomeration, chilling the oil, thereafter removin wax from theoil.

3. A process for ewaxing a wax-containing oil involving separation of wax from oil, which comprises adding coal tar to the oil, thereby to condition the wax-containing oil to cause wax agglomeration, chilling the oil, thereafter removing wax from the oil.

4. A process for dewaxing a wax-containing oil involving separation of wax from oil which comprises, adding to the oil to the extent of less than 2% by weight thereof, a compound contained in coal tar pitch, thereby to condition the wax-containing oil to cause wax agglomeration, chilling the oil, and thereafter removing wax from the oil.

5. A process for dewaxing a wax-containing oil involving separation of wax from oil,

which comprises adding to the oil a comp] pound contained in coal tar pitch, thereby to condition the wax-containing oil to cause wax agglomeration, chilling the oil, thereafter filtering the wax from the oil.

6. A process for dewaxing a wax-containing oil involving separation of wax from oil, which comprises dissolving in the oil a highboiling wax-agglomerating compound contained in coal tar, thereby to condition the wax-containing oil to cause wax agglomeration, thereafter removing wax from the oil.

7. A process for dewaxing a wax-containing oil involving separation of wax from oil, which comprises dissolving in the oil a high-boiling wax-agglomerating compound contained in coal tar, thereby to condition the wax-containing oil to cause wax agglomeration, chilling the oil, thereafter removing wax from the oil.

8. A process for dewaxing a wax-contain- I ing oil involving separation of wax from oil which comprises adding to the oil a high-boils ing wax-agglomerating compound contained in coal tar. thereby to condition the wax-containing oil to cause wax agglomeration, keeping said oil at temperature in excess of 10 F. during addition of said compound, thereafter chilling the'oil to a temperature below 10 F., and removing wax from the oil.

9. A process for dewaxing a wax-containingoil involving separation of wax from oil, which comprises dissolving in the oil an extract of coal tar containing a. high-boiling wax-agglomerating compound of coal tar, thereby to condition the wax-containing oil to cause wax agglomeration, keeping said oil at a temperature in excess of 10 F.-during the addition of said extract, thereafter chilling the oil to a temperature below 10 F., and removing Wax therefrom.

10. In the art of dewaxing wax-containing oils involving separation of wax from oil, the step of preparing the oil for separation of wax therefrom, which comprises adding coal tar pitch to the oil, thereby to condition the waxecontain ing oil to cause wax agglomeration.

11. In the art of dewaxing a wax-containing. oil involving separation of wax from oil the step of preparing the oil for separation o wax therefrom, which comprises adding to the oil a wax-agglomerating extract of coal tar containing at least one of the higher boiling compounds of coal tar, thereby to condition the wax-containing oil to cause wax agglomeration.

12. In a process for dewaxing a wax-containing oil involving separation of wax from oil, the steps which comprise diluting the oil with a solvent which will not to substantial extent react with the oil, adding-to the